Bearing mechanism for centrifuge assembly

ABSTRACT

A fluid system for separating materials in each of a plurality of batches which are simultaneously washed by forcing a fluid through a centrifuge, provides independent pressure heads for each batch to enable flow of equal volumes through said batches, respectively.

United States Patent Schlutz et al.

BEARING MECHANISM FOR CENTRIFUGE ASSEMBLY Inventors: Charles A. Schlutz,Glenview; Stanley J. Sedivy, Chicago Ridge; Charles R. Memhardt, MortonGrove, all of I11.

Assignee: Baxter Laboratories, Inc., Morton V 959 1 Filed: Nov. 16, 1970Appl. No.: 97,407

Related US. Application Data Division of Ser. No. 713,595, March 18,1968, Pat. No. 3,561,672.

U.S. Cl .308 15 Int. Cl. ..Fl6c-35/02 Field of Search ..308/3 R, 3.9, 15

11] 3,719,406 March 6, 1973 [56] References Cited UNITED STATES PATENTS2,178,322 10/1939 Colgin ..308/3 R 3,442,559 5/1969 Horvath et a1..308/15 Primary Examiner-Milton Kaufman Assistant Examiner-BarryGrossman Attorney-Walter C. Kehm and Richard J. Reilly [57] ABSTRACT Afluid system for separating materials in each of a plurality of batcheswhich are simultaneously washed by forcing a fluid through a centrifuge,provides independent pressure heads for each batch to enable flow ofequal volumes through said batches, respectively.

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BEARING MECHANISM FOR CENTRIFUGE ASSEMBLY This application is a divisionof application Ser. No. 713,595, filed Mar. 18, 1968, now US. Pat. No.

The present invention relates to centrifugation. More particularly theinvention relates to centrifugal apparatus for use in washing.Specifically the invention relates to an assembly, including acentrifuge, for washing particles such as red blood cells.

Heretofore it has been known to wash particles by using centrifugingmeans. The principles generally relating to such particle washing havebeen effectively applied in washing red blood cells, particularly forreconstitution following treatment with such reagents as glycerol,polyvinyl pyrrolidone and the like for cell protection. Two heretoforeknown systems for reconstituting preserved red blood cells by theaforestated technique have gained significant practical success.

I One thereof embodies the teachings of U.S. Pat. No.

2,906,453. The other thereof embodies the teachings of US. Pat. No.3,347,454 and is assigned to the assignor of the present application.

While the apparatus of both prior systems are practical for washingpreserved red blood cells in single batches, neither they, nor any ofheretofore known means, is adequate effectively and efficiently forwashing a plurality of batches of preserved red blood cellssimultaneously. That is to say, while simultaneous multi-batch washingcould be practiced in accordance with heretofore known teachings,thereto attendant inefficiencies would increase costs inordinately. Inconsequence, prior to the present invention, washing of red cells inmore than one batch at a time in a given centrifuge assembly has beenneither practical nor conventionally practiced, except experimentally.The inefficiencies result from differential resistance to flow of washfluid generated in material comprising the batches simultaneously beingprocessed. The phenomenon is such that wash fluid in ever increasingvolume flows through one of the batches while it increasingly bypassesany other.

another sense the objects are effected by a process in which material tobe washed is separated into a plurality of batches which aresimultaneously centrifugally spun. While they are spinning influentunder the force of an independent pressure head is flowed through eachof the batches; and efflu'ent from said batches is collected in volumescorresponding to the volumes of influent flowed through said batches.

The foregoing and other objects, features and advantages of theinvention will become more apparent upon consideration of thefollowingdescription and appended claims, when considered in conjunctionwith the accompanying drawings wherein the same reference character ornumeral refers to like or corresponding parts throughout the severalviews.

On the drawings:

1 is a fragment of a vertical sectional view through a centrifugeassembly embodying the present invention, some parts being shown inelevation and other parts broken away, a pair of containers being shownat an angle 90 from actual aspect and in a nonspinning condition.

FIG. 2 is a flow scheme of said assembly, the containers being shown ina spinning condition.

FIG. 3 is a top plan view of a distributor-collector comprising saidassembly.

FIG. 8 is a view according to the line 8-8 of FIG. 7

- but with the cover shown.

It is an object of the present invention to provide an improved processand assembly for centrifugal washmg.

It is another object of the invention to provide improved process andapparatus for centrifugally washing particles, particularly, red bloodcells.

It is a further object of the invention quickly and efficiently toreconstitute red blood cells which have been treated withcryo-protective agents. I

It is an additional object of the invention to enable washing of aplurality of batches of particles, particularly red blood cells,simultaneously.

Moreover, it is an object of the invention to prevent inefficientmaterial separation resulting from differential resistance to flow in aplurality of batches during simultaneous washing thereof in acentrifuge.

The foregoing objects are effected, in a washing centrifuge assemblyhaving a rotor and a pair of containers supported from said rotor forrotation therewith, by charging means for moving influent into each ofsaid containers under an independent pressure head as said rotor spins,and discharging means for. collecting effluent from each of saidcontainers in a volume corresponding to influent moved into saidcontainers. In

FIG. 9 is a side elevational view of fluid control means comprisingsaidassembly, a pair of clamping members being shown abnormally in oppositeconditions.

FIG. 10 is a view according to the broken section line l0l0 of FIG. 9.

FIG. 11 is a view according to the line 11-11 of FIG. 1, a medial partbeing broken away.

FIG. 12 is a scheme of wiring for said assembly.

Referring now more particularly to FIG. 1, there is shown a washingcentrifuge assembly 15 comprised of a housing or outer shell 17 only anupper portion of which is shown. Within chamber 19 of shell 17 acentrifuge rotor 21 is concentrically disposed for rotation. Rotor 21has a hub 25 which is mounted co-rotationally with a driven spindle 27,the latter member being suitably connected to prime mover means (notshown). A plurality of radial members 26 (only two of which are shown)project outwardly from hub 25. A plurality of arms 29, arranged inparallel pairs, project eccentrically from adjoining of members 26. Apin 33 which is circular in cross section extends through each of arms29 for projection from opposite arm faces 31. Adjoining projections ofpairs of pins 33 are engaged by opposed pairs of arcuate shoulders 35 ofa plurality (herein shown as a pair) of receptacles 23 and 24 forswinging support of said receptacles radially from rotor 21. Apart fromevident structural variation, said receptacles may be constructedaccording to co-pending application Ser. No. 672,125, assigned to theassignee of the present application.

Container means comprising a plurality of containers 37 and 38, whichmay be fashioned according to said co-pending application, are disposedin receptacles 23 and 24, respectively, in a manner such that eachcontainer is a supported from said rotor for rotation therewith.Material to be processed, herein shown as particles 36 such as preservedred blood cells, is divided into a plurality of batches which may be ofequal size, and held in containers 37 and 38 for spinning forcentrifugation simultaneously with rotationof rotor 21. The invention,however, is not limited to washing simultaneously only one pair ofbatches. More can be washed simultaneously. Nor is the invention limitedto washing particles, inasmuch as washing of materials in other physicalforms is also comprehended.

In the illustrated embodiment, an inverted coneshaped base provides aseat 39 in each of the receptacles 23 and 24 for an associated ofcontainers 37 and 38. A cap 41 for each of receptacles 23 and 24 has apair of bores through which an influent duct 43 and an effluent duct 45extend for fluid circulation through each of said containers. The partsare proportioned so that a flange 47 on each of said caps will snuglyseat against a rim 49 of a corresponding receptacle as a result ofcentrifugal force when the parts assume the relationship shown in FIG.2. However, when receptacles 23 and 24 are in the condition of FIG. 1the normal pressure under which each container is filled with itsmaterial to be washed may hold each flange 47 spaced from associated rim49.

Fluid control means responsive to centrifugal force comprises acentrifugal clamp assembly generally designated 51 (FIGS. 1, 9 and whichis secured by fasteners such as screws 53 to the top of hub forcorotation with rotor 21. Said fluid control means has a first conditionin which ducts 43 and 45 are shut to block flow into and out ofcontainers 37 and 38 and a second condition in which said ducts are openfor flow into and out of said containers. To that end, clamp assembly 51comprises a body 55 having a plurality of wells 56 and 57 which areherein shown of like profile and disposed to correspond with thedisposition of containers 37 and 38, herein shown as being in diametricopposition. Clamping means comprising a clamping mechanism 58 associatedwith each of containers 37 and 38 is disposed in each of wells 56 and57, respectively. A block 59 comprises each clamp mechanism 58 and isproportioned to slide centrally and outwardly within the limits of itsassociated well along a floor 60 defining such well. A cover 93 (FIG. 9)suitably removably held on body 55 closes wells 56 and 57 from above totrap in each thereof an associated block 59.

Each block 59 has a plurality (herein shown as two) of outwardlyopening, horizontally spaced apart bores 61 and 62 which accommodatespring means comprising a pair of compression springs 63 and 64,respectively. The outer ends of each pair of the latter members bearagainst the inner surface 65 of an associated of outer sidewalls 68 and70 respectively defining wells 56 and 57 for biasing each block inwardlyor centrally. Each block 59 carries a generally T-shaped clamp member 67which is secured thereto by a suitable fastener such as a screw 69. Thestem 71 of each clamp member comprises a radial arm which is slideablyarranged for radial extension in a slot 73 in body 55, said slotsfashioned so that wells 56 and 57 open through sidewalls 68 and '70.Each clamp member 67 also comprises a pair of clamping extensions 75 and76 integral with, and projecting horizontally in opposite directionsfrom, an associated stem 71. Under normal tensioning of each pair ofsprings 63 and 64 its clamping extensions are urged toward an adjoiningof sidewalls 68 and 70, as illustrated to the right of FIGS. 9 and 10.Said springs, however, are tensioned so that under centrifugal forcegenerated when receptacles 23 and 24 have assumed the extreme positionof FIG. 2, its block 59 will be thrown outwardly to the outer limits ofits recess 57 thereby causing projection of corresponding clampingextensions 75 and 76 from the body 55, as illustrated to the left ofFIGS. 9 and 10. It is appreciated that all of the clamping mechanisms 58simultaneously will assume the condition shown either to the right or tothe'left of FIGS. 9 and 10; and that the showing of both conditions ineach view is solely for the purpose of illustrating alternate extremes,which normally will not be present simultaneously.

Each pair of extensions 75 and 76 is fashioned to generate a pair ofrecesses or pockets 77 and 78 through which influent and effluent ducts43 and 45 of an associated of containers 37 and 38 project. Each pair ofsaid recesses is proportioned so that when an associated clamp member 67is in its first condition, as shown to the right of FIGS. 9 and 10, flowin corresponding ducts 43 and 45 will be clamped shut. Whereas, whensuch clamp member is in its second condition illustrated to the left ofFIGS. 9 and 10, said last mentioned ducts will be unclamped to permitunimpaired flow therethrough.

To facilitate clamping, each of sides 68 and has a pair of horizontalelevations 81 and 83 which project in opposite directions from anassociated slot 73. At its outer end each of extensions and 76 has apair of enlarged ears 85 and 87 which are associated in a U-shape andproportioned for engagement about associated of elevations 81 and 83 ina manner illustrated tothe right of FIG. 9 for clamping correspondingducts 43 and 45.

Distributor means or a fluid handling mechanism comprising adistributor-collector 89 controls flow of fresh influent or wash fluidto and spent effluent or waste from the material contained in containers37 and 38. In terms of the influent, distributor-collector 89 isdisposed upstream of clamp assembly 51 from which it.

projects upwardly. The distributor-collector comprises relativelyrotatable first and second parts, being a cupshaped rotor 97 and atherein concentrically associated cylindrical stator 105 (FIG. 4). a Amale component (FIGS. 1, 4 and 5) carried from the lower wall 99 ofrotor 97 is removably keyed or snugly engaged in an opening or hole 91(FIG. 10) formed in body 55 for transmission of torque of rotor 21 torotor 97 for co-rotation of said rotors. Rotor 97 has an upwardlyextending cylindrical sidewall 107 which defines an upper opening 108.The latter is closed by a cap 101 having an aperture 109 and secured tothe top of sidewall 107 by fasteners such as screws m3, only one ofwhich is numbered in FIG. 3.

The outside diameter of stator 105 is less than the inside diameter ofrotor 97 by reason of which a space 1 13 is formed about said stator,said space being closed at the top and bottom by cap 101 and wall 99,respectively. Said stator has a lower end portion 106 which is journaledin wall 99, and a medial portion which is journaled in the aperture ofcap 101 and an enlarged head 111 which projects upwardly from the rotorand is arranged in bearing association with the top of cap 101.

Chamber defining means comprise a plurality of annular flexible sealingmembers 115, 117, 119 and 121 which are arranged in vertically spacedhorizontal planes with the upper sealing member 121 disposed against cap101 for dividing space 113 into a plurality of vertically spacedchambers 123, 125, 127 and 129. The circumferences of the sealingmembers snugly engage the inner surface of rotor wall 107 while theinner surfaces of said sealing member snugly engage the outer surface ofstator 105. Thereby each of chambers 123, 125, 127 and 129 is sealedfrom the others thereof and is defined by an inner wall comprising asection of stator 105 and an outer wall comprising a section of rotor97. A pair of apertures in the chamber walls comprise inlet and outletmeans for said chambers and accordingly distributor-collector 89.

In the present embodiment each of the receptacles 23 and 24 isassociated with a pair of said last mentioned chambers in a manner suchthat one of each pair is an influent chamber and the other thereof is aneffluent chamber. In the present and preferred embodiment of theinvention the lowermost chambers 123 and 125 are influent chambers ofwhich chamber 123 is associated with receptacle 24, whereas chamber 125is associated with receptacle 23. To that end, the upstream end portion129 of duct 43 from receptacle 24 projects through one outlet opening inwall 107 in a fluid tight seal for fluid communication with chamber 123.On the other hand, the upstream end portion 131 of duct 43 fromcontainer 23 extends through the other outlet opening in wall 107 in afluid tight seal for fluid communication with chamber 125. In thepresent and preferred embodiment, chambers 127 and 129 are effluentchambers which are disposed above influent chambers 123 and 125 and arein fluid communication, respectively, with receptacles 23 and 24. Forthat purpose the upper end portion 133 of duct 45 associated withreceptacle 24 projects through one inlet opening in wall 107 in a fluidtight seal for fluid communication with chamber 127. The upper endportion 135 of duct 45 associated with receptacle 23 projects throughthe other inlet opening in wall 107 in a fluid tight seal for fluidcommunication with chamber 129.

By placing influent chambers 123 and 125 below the effluent chambers,the likelihood of contamination of influent by effluent because offaulty seals in distributor-collector-89 is minimized. Moreover, thepressures generated within the system are such that downstream ofcontainers 37 and 38 the effluent paths may be combined, if desired,with impunity.

Stator 105 has a plurality of vertical bores 137, 139, 141 and 143(FIGS. 4, 5 and 6) which open through the top of stator head 111. Thelower ends of bores 137, 139, 141 and 143, respectively, communicatewith chambers 123, 125, 127 and 129. By reason of the Charging means formoving influent or wash fluid into containers 37 and 38 and through thebatches therein contained comprises a pump 153 (FIG. 2) which isarranged in fluid communication with influent bores 137 and 139 througha pair of flexible conduits 145 and 147. Said conduits together withdistributor collector 89 and ducts 43,43 comprise means defining anindependent path or influent pathway for each of containers 37 and 38and extending between said containers and the pump. Pump 153 may be ofthe roller type for irnpelling substantially equal volumes of influentunder independent pressure heads into conduits 145 and 147 andaccordingly containers 37 and 38.In the present embodiment, movement ofinfluent through each system is simultaneous; however other thansimultaneous influent movement may be desirable under washing conditionsother than that specifically described herein.

Fluid from a reservoir 233 supplies influent for pump 153 by gravity.The reservoir is also in direct fluid com.- munication with conduits 145and 147 through a pair of tubes 235 and 237, which bypass the pump forgraviforegoing, bores 137 and 139 are influent bores whereas bores 1'41and 143'are effluent bores.

'ty feed into containers 37 and 38, respectively, for a reason to becomeapparent from ensuing description.

Discharging means for collecting effluent or spent wash fluid comprisesan effluent tank 155, which is in fluid communication with bores 141 and143 through duct means herein comprised of ducts 149 and 151,respectively. A bearing mechanism generally designated 15 (FIGS. 1 and1-1) for the relatively stationary part of .a rotational assemblycomprises a retainer 159 having a pair of spaced apart fingers 161 and-162 which define an elongated recess 163 in which an upper reducedportion 165 of stator head 111 is intimately engaged for slidingnormally of an expansion band or bar 167 when the latter is in assembledcondition. The retainer is captured in a pocket 166 formed in medialsection 168 of expansion bar 167 to permit sliding of the retainerlongitudinally of said bar in opposite directions in response tocorresponding stresses during rotation of rotor 97.

Bar 167 comprises a' pair of opposed end sections 158 and 160 at leastone of which is telescopically connected to medial section 168. Said endsections carry a pair of opposed fittings or adaptors 169 and 177 havingoutwardly extending hooks 171 and 181, respectively for projection intoa mating aperture formed in the lower end of a skirt 173 (FIG. 1) hungin the top opening of the centrifuge from shell 17. An annular cushionor pad 175 is shown disposed between the said shell and skirt 173 forcushioning evident forces brought to bear. In consequence of theforegoing construction, distributor-collector 89 will be held erectduring rotation of rotor 21, fingers 161 and 162 being proportioned toprevent removal thereof. However, bar 167 may be contracted to disengagehooks 171 and 181 from skirt 173 for removing said distributor-collectorfrom the centrifuge. Thereafter, release of the rotor 97 from bar 167 byremoving the stator head from recess 163 can be achieved. 1

In the illustrated embodiment section 158 comprises a vertical plate 185with which hook 171 is integral and a vertical plate 189. The inner endportions of said plates are arranged in slidingassociation with theoutside of opposed parallel faces of medial section 168.

The outer end portions of said plates are separated by a spacer 187 thewidth of which is equal to the width of section 168 from the proximateend of which said spacer is spaced. To one face of said spacer, plate185 is secured by fasteners such as rivets 179 and to the opposite faceof said spacer, plate 189 is secured by fasteners such as rivets 191.One end portion of medial section 168 has a well 193 in which one end ofa compression spring 195 is mounted for extending block 187 andaccordingly fitting 169 longitudinally of bar 167 and for holding saidbar in mounted position in the centrifuge.

In addition to the condition shown in FIG. 11, bar 167 can assume twoother positions according to the condition of latch means 197 which ismounted transversely of said bar from an end portion 199 of section 168.Said latch means comprises a part in the form of a rod 201 which extendsthrough a transverse opening or slot 223 in section 168 and a pair oftransversely aligned apertures 203 and 205 in telescopic section 158.While the dimension of opening 223 longitudinally of section 168 isconsiderably larger than the diameter of rod 201, the diameter ofapertures 203 and 205 is such that latch means 197 is snugly engaged tolimit its movement in section 158 to transverse sliding. The diameter ofaperture 205, however, is larger than aperture 203 to accommodatesliding of another part of said latch means, said other part being anannular bearing extension 206 of a bearing cap 207. The latter issecured by a screw 209 on one end portion 211 of rod 201 which projectsnormallyfrom the outer face of plate 189. A spring retainer 213 in theform of a cup is secured by a screw 215 to the opposite end portion 217of rod 201 said opposite end portion projecting normally from plate 185.A compression spring 219, which is disposed about end portion 217, hasone end disposed in retainer 213 and the other end bearing againstvertical plate 185 for drawing cap 207 into engagement with the outersurface of plate 189. The parts are proportioned so that under normalbiasing bearing extension 206 will be drawn inwardly of plate 189 into areduced part of opening 223.

That is to say, opening 223 has a pair of parallel limiting walls 225and 227 spaced apart longitudinally of section 168. These walls definethe limits of movement of rod 201 longitudinally of bar 167. Within therecess 223 there is generated adjacent plate 189 annular shoulder 229within the annulus of which bearing extension 206 is normally biased.The diameter of the annulus formed by the shoulder 229 is less than thespace between walls 225 and 227 so that while the parts are conditionedas in FIG. 11 contraction of bar 167 will be limited by engagement ofthe extension 206 and the shoulder 229. The parts are proportioned sothat this extent of contraction is not enough to permit removal of bar167 from the centrifuge. However, it is adequate for accommodatingvariation in the distance across (herein shown as a diametric cord)skirt 173 and provided for bar 167 in assembled condition.

Yet another condition of the bar 167 is required for removing-it fromthe centrifuge. This is achieved by pushing rod 201 upwardly withrespect to FIG. 11 against the bias of spring 219 until cup 213 engagesplate 205. The parts are proportioned so that upon the last occurrence,extension 206 will be removed from recess 223. Accordingly, rod 201 willbe free for engaging wall 225. In such last condition bar 167 will havebeen contracted sufficiently to permit its removal from the centrifuge.

The foregoing combination enables economical employment of a disposablecollector-distributor 89 for each washing operation whereby likelihoodof introduction of contaminants may be minimized.

Flow through the system defined by passaged means comprising ducts 43,45, 149 and 151 and conduits 145 and 147 is controlled throughelectrical circuitry (FIG. 12) comprising three solenoids 239, 241 and243. The latter together with said circuit are arranged within a controlbox 245 (FIGS. 7 and 8) having an upper horizontal plate 247 relative towhich a cover plate 249 is hingedly arranged for securance by a latchingassembly 255. In the present embodiment, the latching assembly comprisesa post 257 which projects upwardly from plate 247 through a registeringaperture in the cover plate 249 so that adjoining flat surfaces of saidplates may be releasably held in engaged association by a lock 259associated with said post.

Plate 247 has a plurality of upwardly opening channels or grooves 261,263 and 265. Pressure feet or pads 267, 269 and 271 carried on the endsof reciprocating arms controlled by solenoids 239, 241 and 243respectively, are arranged for extension through apertures providedtherefor in the bottoms of said channels, respectively. Medial portionsof tubes 235 and 237 are disposed in channel 261. Downstream portions ofducts 149 and 151 are disposed in channel 263. Portions of conduits 145and 147, which are upstream of their communication with tubes 235 and237, are disposed in channel 265. The parts are arranged andproportioned so that when the solenoid is de-energized the flow pathsthrough their associated tubes, ducts and conduits are open. However,while plate 249 is closed (its normal operating condition) and asolenoid is energized, its pressure foot will be projected to clamptherewith associated ducts, conduits and tubes to cut their flow paths.

For operating the device a plug 273 (FIG. 12) for connecting the powercircuit 275 of the assembly to a volt A.C. power source (not shown) isprovided. The primary of a transformer 277 is arranged in series inpower circuit 275 which becomes energized upon closure of apush-to-make, push-to-break, double pole switch 279. In the presentembodiment of the invention, the secondary of transformer 277 is a 24volt coil with which a selenium rectifier 281 is arranged in parallelfor developing a D.C. effect. Simultaneously with the energization oftransformer 277, a lamp 305, which may be carried from a switch box 307,will light by reason of connection to one terminal 287 of rectifier 281through a conductor 309 and thereby indicate the condition of the powercircuit 275. The other side of said rectifier is connected to a plane ofreference potential, herein shown as ground 282.

One terminal of each of solenoids 239, 241 and 243 is connected throughva conductor 283 to ground. The other terminal 285 of solenoid 239 isconnected to terminal 287 of. said rectifier through a switch 289 of anormally closed relay 291. The other terminal 293 of solenoid 241 isconnected to terminal 287 of said rectifier through a switch 295 of anormally closed relay 297. The other terminal 299 of solenoid 243 isconnected to terminal 287 of said rectifier through a switch 301 of anormally closed relay 303. By reason of the foregoing construction, oncethe plug 273 has been connected to a power source and the switch 279closed, solenoids 239, 241 and 243 will become energized whereuponpressure feet or pads 267, 269 and 271 will be conditioned for cuttingflow in the system.

A grounded coil 309 (upper left of FIG. 12) of a normally closed relay311 is energized upon closure of switch 279 by reason of a conductor.313 which connects one side of said last mentioned-coil and terminal 285whereupon switch 315 of relay 311 will open. Relay 311 is arranged forlighting a lamp317 by reason of a circuit wire 319 which will connectsaid last lamp to the selenium rectifier through a conductor 318 whenswitch 315 is in closed condition.

To commence operation of the centrifuge, a normally open switch 321which is mounted in a housing 324 is manually depressed momentarily toclosed condition. Switch 321 is connected in parallel with the startingswitch of the circuit of a centrifuge motor or prime mover means fordriving spindle 27 in a manner such that once closed, said circuit willcontinue to operate the centrifuge regardless of the condition of switch321 until stopped by means to be hereinafter described. Said motor maybe of conventional construction and accordingly it together with itscircuit have been omitted in the drawings.

Relay 291 is included in multiple assembly 323 which also comprises anormally open relay 325 and a common coil 327. The latter member isconnected to the circuit (not shown) of the centrifuge motor. Thereby,upon closure of switch 321, switch 329 of relay 325 and switch 289,which are both magnetically coupled to the coil 327, respectively, willclose and open. When the switch 289 opens, current flow to solenoid 239as well as to coil 309. becomes interrupted. Thereupon pressure foot 267will retract to open tubes 235 and 237 for establishing fluidcommunication between reservoir 233 and containers 37 and 38, providedrotor 21 is spinning fast enough for clamp assembly l-to have opened. Inconsequence thereof the system will fill with influent and initial flowthrough the system will be by gravity. Also, switch 315 will assume itsnormally closed condition causing lamp 317 to light, thereby indicatingthe open condition of tubes 235 and 237 in control box 245.Simultaneously, because one terminal 331 of relay 325 is connected toterminal 287 while the other terminal 333 of said last relay isconnected to a grounded lamp 335 mounted in housing 324 through acircuit conductor 337, lamp'335 will light as an indicator; of theoperating condition of the centrifuge. I

The precaution of preventing initial filling of the system until apredetermined centrifugal force is reached tends to prevent backflowfrom containers 37 and 38 and possible contamination of influent.Moreover, accidental emptying of container contents is also prevented bythus keeping the system closed.

Stopping of gravity flow of influent is effected by a normally openpush-to-make, push-to-break, double pole switch 339 which is mounted ina housing 341. Switch 339 may be operated manually as shown herein or inresponse to an electrical effect generated in a known manner in responseto a conditionsuch as a lapse of time or color or density of effluentaccumulating in ducts 149 and 151. Once closed, switch 339 will be heldin closed condition by reason of magnetic coupling to a coil 345 whichis mounted in housing 341. Said coil is immediately energized on closingof switch 279 through a relay 347 whose switch 349 is normally biased toclosed condition and which is connected to terminal 287 through acircuit wire 351. A voltage reducing resistance 343 is interposed in aconductor 353 which connects coil 345 to relay 347.

A circuit wire 355 connects one terminal 357 of switch 339 to a groundedlamp 360, which when lit indicates operation of pump 153 and pumpgenerated flow through the system. Said terminal 357 is arranged forconnection, through said last switch when closed to rectifier terminal287 through a circuit conductor 359. The other terminal 361 of switch339 is connected to one side of a grounded relay coil 363. Coil 363 isdisposed in a housing 367 for magnetic coupling to an assembly of relayscomprising heretofore described relays 297 and 303 and additional relays369 and 371. Switches 373 and 375 of relays 369 and 371 are normallybiased to an open condition. The arrangement is such that when coil 363is energized switches 373 and 375 will be magnetically moved to closedcondition whereas switches 295 and 301 will be opened.

Upon opening of switches 295 and 301 circuits for solenoids 241 and 243are opened and said last solenoids accordingly become de-energized.Thereupon pressure feet 269 and 271 move to non-clamping condition andfluid communication becomes established between pump 231 and containers37 and 38 and between said containers and effluent tank 155.Simultaneously, solenoid 239 becomes energized by reason of closure ofrelay 369. Accordingly pressure .foot 267 moves to closed condition tointerrupt flow in tubes 235 and 237. The last result is effected becauseone terminal 377 of relay 369is connected to terminal 287 of rectifier281 through a circuit wire 379 and the other terminal 380 of said relay369 is connected to the plane of reference potential through a circuitassembly in-' cluding conductor 381. The latter connects relay 369 to aterminal 383 of a relay 385 In turn terminal 383 is connected by acircuit wire 387 to a terminal 389 of relay 289. However, relay 289 isbypassed by a circuit wire 391 which connects terminal 389 to terminal285 of solenoid 239 for connection of the latter through bypass 391 torelay 369. In consequence of the foregoing, when relay 369 is closed thecoil 309 of relay 315 will also become energized to magnetically impelswitch 315 to an open condition thereby to extinguish lamp 317simultaneously with the closure of tubes 235 and 237. When solenoids 241and 243 are energized, pump 153 is'also actuated by reason of closure ofrelay 371 which is serially connected between a pair of volt A.C.circuit wires 393 and 395 comprising the circuit of said pump.

For operation, the pressure of pump 153 is set at a level sufficient toovercome the centrifugal force created and to effect a flow throughcontainers 37 and 38 for washing material 36 and delivering effluent totank 155 corresponding to the influent volume. The rate of flow can becontrolled in accordance with requirements and factors including thecharacter. of the material being washed. None of these factors iscritical to the present invention and accordingly details of the processdepending upon the character or type of material are omitted.

Suffice it to say that washing may be stopped at any desired time byclosing a double pole, push-to-make, push-to-break switch 397 which ismounted in a housing 399. Said last switch may be manually operated (asillustrated) or automatically in response to an effect generated bywell-known means according to lapse of time or a physical characteristicof the effluent. Once closed, switch 397 may be held in closed conditionby the magnetic force induced about a grounded coil 401 which from aterminal 403 is connected to heretofore defined circuit wire 359 througha voltage lowering resistance 405. However, switch 397 can also bereleased by'breaking the circuit to coil 401 by depressing a nor mallyclosed interruptive switch 407 disposed in the circuit of said lastcoil.

Upon initial closure of switch 397 both of its terminals 409 and 411become operatively connected to rectifier terminal 287 through circuitwire 359. In turn terminal 409 is connected to a grounded lamp 413 whichaccordingly will light when switch 397 is closed to indicate the closedcondition of such last switch. The other pole 411 energizes groundedcoil 415 of relay assembly 417. The latter assembly includes theaforementioned relays 347 and 385 and an additional and normally closedrelay 419. Accordingly, when coil 415 is energized by reason of closureof switch 397, switch 386 of relay 385 will be magnetically moved toclosed condition while the switches 349 and 420 of relays 347 and 419will be magnetically moved to open condition. Relay 419 is connected inseries with the circuit of the centrifuge motor (not shown) andaccordingly when it opens the centrifuge will stop. Relay 347, becauseof its interposition between terminal 287 and coil 345, will interruptthe circuit to said last coil when open. Accordingly, magnetically heldswitch 339 will be released and current flow to lamp 360 will terminate.In consequence lamp 360 will extinguish, relays 369 and 371 will openand relays 297 and 303 will be restored to a closed position. As aresult, pump action. will stop (because relay 371 is open); solenoid 239will be deenergized (because relay 369 is open) and solenoids 241 and243 will become de-energized (by reason of the opening of the respectiveof relays 297 and 303).

By reason of the foregoing construction controlled washing volumes canbe forced into each of containers 37 and 38 notwithstanding differentresistances to flow in said containers. In prior devices while the totalwash volume can be controlled, the volume to each container isuncontrollable because differential resistance in the containers causesthe paths of wash fluid which comes from a common pressure head to movein an uncontrolled fashion. In consequence of the invention,simultaneous washing of a plurality of batches of particles can beachieved in a period substantially no longer than the time required forwashing a single batch. Thereby, for the first time there is provided awashing centrifuge assembly practical for simultaneous processing of aplurality of batches of materials.

The process described has been practiced effectively in reconstitutingthawed red blood cells which theretofore had been preserved by freezingand protected from freeze damage by various cryoprotective agents. Amongthe latter which have been removed are glycerin, an intracellular agentused in high and low concentrations, and polyvinyl pyrrolidone, anextracellular agent.

For removal of glycerinating agent from highly glycerinated frozen redblood cells, a pair of batches, each of which comprises the yield of 500milliliters of whole blood, is first thawed arid thereafter spun in ahigh speed centrifuge for a period sufficient for separating the cellsand available liquid. The supernatant is then removed and the red bloodcells of each batchare transferred to one of containers 37 and 38,respectively, for processing in accordance with the invention.

A first wash solution, preferablyan aqueous manitolsaline, forosmotically shrinking the red blood cells and thereby increasing theirdensity, is first forced through each batch by independent pressuremeans for a period sufficient to condition the cells for readyseparation from environmental fluid when centrifuged. Thereafter, asecond wash solution having a decreasing concentration or gradient tocell shrinking agent is used to gradually decrease the level of cellularshrinkage to a nullity as a density differential between cells andenvironmental fluid can be maintained under centrifugal force withoutsaid agent. After the manitol has been completely dissipated the cellswill restore to normal size and washing may be completed with hypertonicwash solution of about 5% glucose in normal saline. The foregoingprocedure suitably reconstitutes frozen red blood cells for use intransfusion.

The hypertonic solution may omit the 5 percent glucose in which eventthe decreasing manitol gradient may be established with isotonic saline.Moreover, if desired, the original wash solution may be omitted and allwashing may be done with normal saline or the hypertonic solution. Insuch event, however, great care should be exercised to avoid high redcell loss during initial periods of washing. Such likelihood isminimized by manitol in the first wash solution which causes an osmoticsqueeze on the red cells. Thereby, cell density is increased enablingimproved separation of red cells from the less dense glycerinating agentfor removal with effluent.

As many substitutions or changes could be made in the above describedconstruction and process, and as many apparently widely differentembodiments of the invention within the scope of the claims could beconstructed without departing from the scope and spirit thereof, it isintended that all matter contained in the accompanying specificationshall be interpreted as being illustrative and not in a limiting sense.

WHAT IS (ILAIMED IS:

1. In a centrifuge assembly having a stator, and a rotor mounted withina housing member arranged for rotation about said stator:

a mounting band having opposite end portions arranged for securance tosaid housing member;

a retainer carried from a medial portion of said mounting band forreleasably holding said stator; and

means permitting movement of said stator and retainer longitudinally ofsaid band responsive to stresses generated during rotation of saidrotor.

extended position for securing said mounting band to said housingmember.

4. The centrifuge assembly of claim 3 in which said mounting bandsections are telescopically arranged, one of said sections having anopening, a stop member carried by the other of said sections andpositioned within said opening to prevent longitudinal movement of saidsections beyond a maximally extended first position and a maximallycontracted second position.

1. In a centrifuge assembly having a stator, and a rotor mounted withina housing member arranged for rotation about said stator: a mountingband having opposite end portions arranged for securance to said housingmember; a retainer carried from a medial portion of said mounting bandfor releasably holding said stator; and means permitting movement ofsaid stator and retainer longitudinally of said band responsive tostresses generated during rotation of said rotor.
 1. In a centrifugeassembly having a stator, and a rotor mounted within a housing memberarranged for rotation about said stator: a mounting band having oppositeend portions arranged for securance to said housing member; a retainercarried from a medial portion of said mounting band for releasablyholding said stator; and means permitting movement of said stator andretainer longitudinally of said band responsive to stresses generatedduring rotation of said rotor.
 2. A centrifuge assembly according toclaim 1 in which said retainer defines slot means disposed transverselyof said mounting band for retaining said stator, while permittingmovement of said stator transversely to said band responsive to stressesgenerated during rotation of said rotor.
 3. The centrifuge assembly ofclaim 2 in which said mounting band comprises a pair of sectionsarranged for relative axial movement for extending and contractingtogether, and means for biasing said sections into extended position forsecuring said mounting band to said housing member.